This application claims benefit of Japanese Applications No. 11-163962, filed on Jun. 10, 1999; and No. 11-273067, filed on Sep. 27, 1999, the contents of which are incorporated by this reference.
This invention relates to a reference frame to be suitably used for surgical operations including those of brain surgery and also to a marker to be used with such a reference frame. The present invention also relates to a surgical operation navigating system using such a reference frame.
In the field of surgical operations including those of brain surgery, it is highly important to accurately determine the positional relationship between the target portion of the patient for surgery and the surgical instrument to be used for the operation through measurement. It is also important to establish the positional correspondence between the target portion of the patient and an image of the target portion obtained for examination. The operation of defining the positional relationship between the target portion of the patient and the surgical instrument and also that of defining the positional relationship between the target portion of the patient and an image of the target portion are referred to as operative calibration. Known techniques for operative calibration include the one proposed in R. H. Taylor (ed.), xe2x80x9cComputer-Integrated Surgeryxe2x80x9d, MIT Press, 1996 (hereinafter referred to as Document 1) that utilizes a stationary frame.
N. Hata, et. al, xe2x80x9cDevelopment of a frameless and armless stereotactic neuronavigation system with ultrasonographic registrationxe2x80x9d, Nueorsurgery, Vol. 41, No. 3, September 1997, pp. 609-614 (hereinafter referred to as Document 2) describes the use of a specifically designed reference frame fitted to the patient and used to register the coordinates representing the target portion of the patient and an image of the target portion obtained for examination.
The technique described in Document 1 utilizes a stationary metal frame, by means of which a metal marker is driven into the body of the patient from the body surface like a screw for the purpose of fixing and registration. In other words, this technique is highly invasive to the body of the patient.
According to Document 2, the reference frame is made of acrylic resin and held stationary to the body of the patient by way of the left auditory tube and the nasal projection and a total of four metal cubes are fitted onto the reference frame and used as markers.
Then, the left auditory tube and the nasal projection are made rigid by means of silicone rubber.
Thereafter, the markers are located in a CT image and actually detected by means of a probe on the body of the patient. In actual operation scenes, the doctor carries out the operation while watching the markers as detected by an ultrasonic wave.
However, the method described in Document 2 are accompanied by the following problems.
1) The accuracy of registration using the reference frame is rather poor because the frame is anchored to the body of the patient at two positions to make it held stationary.
2) Once the reference frame is removed from the body of the patient, it is difficult to accurately restore the original posture of the frame because it is anchored to the body of the patient by silicone rubber.
3) The markers cannot be used in an MRI image because they are made of metal.
4) The images of the markers can vary enormously depending on the view angle and hence it is highly difficult to define a position to be probed and the corresponding position in the image obtained for examination because the metal markers have a cubic profile.
5) It is difficult to conduct the surgical operation while leaving the reference frame on the patient and it is also difficult to put a drape on the frame in order to maintain the clean environment of the operation because the frame is large due to its intrinsic structure.
Meanwhile, Japanese Patent Application KOKAI Publication No. 7-311834 proposes an auxiliary device adapted to register images obtained for different examinations by using a reference frame that is a sort of mouthpiece reflecting the impression of the teeth of the patient.
However, the frame as described in the above KOKAI Publication is designed to register images obtained for different examinations and hence cannot suitably be m used for actual surgical operations. For example, a connector that looks like an antenna is used and arranged between the mouthpiece and the forehead of the patient and the markers are put to the front end of the connector so that it is not possible to put a drape on the frame for the surgical operation. In the case of a surgical operation using an endoscope inserted into the body through one of the nostrils of the patient that is attracting attention recently, the connector arranged at the center of the face of the patient obstructs the endoscope trying to enter the body through the nostril. Additionally, the markers are located at upper positions of the mouthpiece. In other words, they are arranged around the oral cavity. Additionally, a total of three markers are arranged on a horizontal plane on the head at the cost of accuracy of registration particularly when images of the brain are taken for brain surgery at a position right above the head. Still additionally, since an upper portion and a central portion of the brain are not covered by the markers, a relatively large error can become involved when computationally determining the coordinate transformation parameters necessary for the registration of an upper portion and an central portion of the head even if the markers can be detected in the images obtained for examination.
Furthermore, in actual operation scenes, there are cases it is impossible to observe the markers on the reference frame in a real space. Such an occasion may arise when the path to be used for the operation is not located near the reference frame or when the markers of the reference frame have to be located at positions that cannot be detected by means of a three-dimensional sensor because of the selected method for the surgical operation.
In view of the above identified circumstances, it is therefore an object of the present invention to provide a reference frame 1) that is structurally stable and can be used during the surgical operation, 2) that can be removably arranged in position when obtaining tomographic images for the purpose of examination and restored to the position prior to the surgical operation and 3) that has markers that can be detected in the tomographic images obtained for the purpose of examination and their positions can be identified on the frame arranged on the body of the patient.
It is another object of the present invention to provide a surgical operation navigator adapted to utilize such a reference frame.
It is another object of the present invention to provide an operative calibration method and an operative calibration apparatus that are flexible enough and adapted to complex paths to be used for surgical operation.
According to a 1st aspect of the present invention, there is provided a reference frame adapted to be fitted to a subject of medical treatment and provided with markers for determining the position or the orientation of the subject, the reference frame comprising:
fixing section for fixing the reference frame with the subject at least three spots along the undulations of the surface thereof; and
three or more than three markers detectable at least ether in an X-ray image or in an MRI image of the reference frame, the markers being to be arranged at predetermined positions not connectable by a straight line.
According to a 2nd aspect of the present invention, there is provided a surgical operation navigating system comprising:
a coordinate computing section for computationally determining the coordinates of markers on a reference frame fitted to a subject of medical treatment in a tomographic image of the subject in terms of a coordinate system uniquely defined for the image for examination, the reference frame having three or more than three markers detectable at least either in an X-ray image or in an MRI image thereof, the markers being arranged at predetermined positions not connectable by a straight line; and
a correspondence computing section for computationally determining the transformation between the coordinate system for the tomographic image for examination and a coordinate system defined for the real space containing the markers on the basis of the coordinates of the markers as determined by the coordinate computing section in terms of the coordinate system for the tomographic image for examination and the coordinates of the markers as determined in terms of the coordinate system for the real space.
According to a 3rd aspect of the present invention, there is provided a marker to be placed with a predetermined relationship relative to a subject of medical treatment to provide a mark for determining the position or the orientation of the subject, the marker comprising:
a hollow outer shell section formed by using a ceramic material; and
a copper sulfate type solution contained in the hollow area of the outer shell.
According to a 4th aspect of the present invention, there is provided a surgical operation navigating system comprising:
a coordinate computing section for computationally determining the coordinates of markers on a reference frame fitted to a subject of medical treatment in a tomographic image of the subject in terms of a coordinate system uniquely defined for the image for examination, the reference frame having three or more than three markers detectable at least either in an X-ray image or in an MRI image thereof, the markers being arranged at predetermined positions not connectable by a straight line;
a first correspondence computing section for computationally determining the transformation between the coordinate system for the tomographic image for examination and a coordinate system defined for the real space containing the markers on the basis of the output of the coordinate computing section and the coordinates of the markers as determined in terms of the coordinate system for the real space;
a second correspondence computing section for computationally determining the transformation between the coordinate system for the real space and a coordinate system uniquely defined for a surgical instrument on the basis of the coordinates of the surgical instrument as determined in terms of the coordinate system for the surgical instrument; and
a third correspondence computing section for computationally determining the transformation between the coordinate system for the tomographic image for examination and the coordinate system for the surgical instrument on the basis of the outputs of the first and second correspondence computing sections.
According to a 5th aspect of the present invention, there is provided a surgical operation navigating system comprising:
a coordinate computing section for computationally determining the coordinates of markers on a first reference frame fitted to a subject of medical treatment in a tomographic image of the subject in terms of a coordinate system uniquely defined for the image for examination, the reference frame having three or more than three markers detectable at least either in an X-ray image or in an MRI image thereof, the markers being arranged at predetermined positions not connectable by a straight line;
a correspondence computing section for computationally determining the transformation between the coordinate system for the image for examination and a coordinate system defined for the real space containing the markers on the basis of the output of the coordinate computing section and the coordinates of the markers as determined in terms of the coordinate system for the real space; and
a correcting section for correcting the result of the correspondence computing section on the basis of the coordinates of a second reference frame as determined during a surgical operation in terms of the coordinate system for the real space.
According to a 6th aspect of the present invention, there is provided a reference frame comprising:
an anchoring mechanism for rigidly anchoring the reference frame to a subject of medical treatment by utilizing at least three undulated spots on the surface of the body of the subject; and
at least three markers arranged on the frame at positions not connectable by a straight line, the markers containing a material adapted to make them detectable at least either in an X-ray image or in an MRI image of the frame.
According to a 7th aspect of the present invention, there is provided a surgical operation navigating system using a reference frame adapted to be rigidly anchored to a subject of medical treatment by utilizing at least three undulated spots on the surface of the body of the subject, the system comprising:
an image acquisition section for acquiring tomographic images of the subject for medical examination with the reference frame fitted to the subject and carrying at least three markers thereon at positions not connectable by a straight line, the markers containing a material adapted to make them detectable at least either in an X-ray image or in an MRI image of the frame;
a marker position detecting section for detecting the positions of the markers in terms of the coordinate system for the tomographic image for examination;
a marker detecting section for detecting the markers on the frame fitted to the subject in the real space; and
a registering section for registering the coordinates of the tomographic image for examination and those of the subject by registering the coordinates of the marker positions as detected by the marker position detecting section and the coordinates of the markers as detected by the marker detecting section.
According to an 8th aspect of the present invention, there is provided a reference frame comprising:
fitting section for fitting the reference frame with a subject of medical treatment at least three spots along the undulations of the surface thereof; and
markers formed by combining a material easily detectable in an image of first examining method and a material easily detectable in an image of second examining method.
According to a 9th aspect of the present invention, there is provided a calibration method for computing positional/orientational transformation between a subject of medical treatment and a tomographic image of the subject by using the corresponding relationship between the coordinates of a first markers fitted to the subject in the image and the coordinates of the first markers in the real space, the method comprising steps of:
fixing second markers other than the first markers to the subject;
determining the coordinates of the second markers in the image by using the coordinates of the markers in the real space and the corresponding relationship; and
computing positional/orientational transformation between the subject and the image of the subject by using the determined coordinates of the second markers.
According to a 10th aspect of the present invention, there is provided a calibration apparatus for computing positional/orientational transformation between a patient to be subjected to a surgical operation a tomographic image of the patient by using the corresponding relationship between the coordinates of a reference frame (first markers) fixed to the patient in the image and the coordinates of the reference frame (markers) in the real space, the apparatus comprising:
a coordinate detecting section for fixing (second) markers other than the reference frame to the patient and determining the coordinates of the markers on the image by using the coordinates of the markers in the real space and the corresponding relationship; and
a registering section for computing positional/orientational transformation between the patient and the image of the patient by using the coordinates of the markers determined by the coordinate detecting section.
According to an 11th aspect of the present invention, there is provided a calibration method for computing positional/orientational transformation between a subject of medical treatment and a tomographic image of the subject by using the corresponding relationship between the coordinates of a reference frame (first markers) fitted to the subject in the image and the coordinates of the reference frame in the real space, the method comprising steps of:
fixing (second) markers other than the reference frame (first markers) to the subject and determining the coordinates of the (second) markers on the image by using the coordinates of the (second) markers in the real space and the corresponding relationship; and
computing positional/orientational transformation between the subject and the image of the subject by using the markers.
According to a 12th aspect of the present invention, there is provided a method of computing positional/orientational transformation between a subject of medical treatment and a tomographic image of the subject, the method comprising steps of:
fitting a reference frame adapted to be removably placed on the subject and provided thereon with a plurality of first markers;
taking a tomographic image of the subject carrying the reference frame thereon and determining the coordinates of the markers appearing in the image of the subject in terms of a coordinate system defined for the image;
fixing a plurality of second markers to the subject carrying the reference frame and determining the coordinates of the first markers and those of the second markers in terms of a coordinate system defined for the real space;
computing the positional/orientational transformation between the coordinate system defined for the real space and the coordinate system defined for the image on the basis of the coordinates of the first markers in the coordinate system defined for the real space and those of the first markers in the coordinate system defined for the image;
determining the coordinates of the second markers in the coordinate system defined for the image by using the coordinates of the second markers in the coordinate system defined for the real space and the positional/orientational transformation; and
computing positional/orientational transformation between the subject and the image of the subject by using the coordinates of the second markers.
According to a 13th aspect of the present invention, there is provided an operative calibration apparatus of computing positional/orientational transformation between a patient to be subjected to a surgical operation and a tomographic image of the patient, the apparatus comprising:
a reference frame to be fitted to the patient, the frame being adapted to be removably placed on the patient and provided thereon with a plurality of first markers;
a first detecting section for taking a tomographic image of the patient carrying the reference frame thereon and determining the coordinates of the markers appearing in the image of the patient in terms of a coordinate system defined for the image;
a second detecting section for fixing a plurality of second markers to the patient carrying the reference frame and determining the coordinates of the first markers and those of the second markers in terms of a coordinate system defined for the real space;
a relationship computing section for computing the positional/orientation transformation between the coordinate system defined for the real space and the coordinate system defined for the image on the basis of the coordinates of the first markers in the coordinate system defined for the real space determined by the first detecting section and those of the first markers in the coordinate system defined for the image;
a coordinate computing section for determining the coordinates of the second markers in the coordinate system defined for the image by using the coordinates of the second markers in the coordinate system defined for the real space determined by the second detecting section and the positional/orientational transformation determined by the relationship computing section; and
a registering section for computing positional/orientation transformation between the patient and the image of the patient by using the coordinates of the second markers determined by the coordinate computing section.
According to a 14th aspect of the present invention, there is provided a calibration method of calibrating the position/orientation of a subject of medical treatment and a tomographic image of the subject by using a reference frame securely fitted to the subject, the method comprising steps of:
fixing markers not found on the reference frame to the subject;
defining the positions of the markers in a coordinate system for the image for examination as defined for the image for examination by using the reference frame; and
registering the coordinates of the coordinate system for the image for examination and the coordinate system for the real space by detecting the positions of the markers in the coordinate system for the real space as defined for the real space containing the subject.
According to a 15th aspect of the present invention, there is provided a calibration apparatus of calibrating the position/orientation of a patient to be subjected to a surgical operation and a tomographic image of the patient by using a reference frame securely fitted to the subject, the apparatus comprising:
markers not found on the reference frame and adapted to be fitted to the patient;
a position defining section for defining the positions of the markers in a coordinate system for the image for examination as defined for the image for examination by using the reference frame; and
an registering section for registering the coordinates of the coordinate system for the image for examination and the coordinate system for the real space by detecting the positions of the markers in the coordinate system for the real space as defined for the real space containing the patient.
According to a 16th aspect of the present invention, there is provided a reference frame adapted to be fitted to a subject of medical treatment and provided with markers for determining the position or the attitude of the subject, the reference frame comprising:
fitting means for fitting the reference frame with the subject at least three spots along the undulations of the surface thereof; and
three or more than three markers detectable at least ether in an X-ray image or in an MRI image of the reference frame, the markers being to be arranged at predetermined positions not connectable by a straight line.
According to a 17th aspect of the present invention, there is provided a surgical operation navigating system comprising:
a coordinate computing means for computationally determining the coordinates of markers on a reference frame fitted to a subject of medical treatment in a tomographic image of the subject in terms of a coordinate system uniquely defined for the image for examination, the reference frame having three or more than three markers detectable at least either in an X-ray image or in an MRI image thereof, the markers being arranged at predetermined positions not connectable by a straight line; and
a correspondence computing means for computationally determining the transformation between the coordinate system for the image for examination and a coordinate system defined for the real space containing the markers on the basis of the coordinates of the markers as determined by the coordinate computing means in terms of the coordinate system for the tomographic image for examination and the coordinates of the markers as determined in terms of the coordinate system for the real space.
According to an 18th aspect of the present invention, there is provided a surgical operation navigating system comprising:
a coordinate computing means for computationally determining the coordinates of markers on a reference frame fitted to a subject of medical treatment in a tomographic image of the subject in terms of a coordinate system uniquely defined for the image for examination, the reference frame hanging three or more than three markers detectable at least either in an X-ray image or in an MRI image thereof, the markers being arranged at predetermined positions not connectable by a straight line;
a first correspondence computing means for computationally determining the transformation between the coordinate system for the tomographic image for examination and a coordinate system defined for the real space containing the markers on the basis of the output of the coordinate computing means and the coordinates of the markers as determined in terms of the coordinate system for the real space;
a second correspondence computing means for computationally determining the transformation between the coordinate system for the real space and a coordinate system uniquely defined for a surgical instrument on the basis of the coordinates of the surgical instrument as determined in terms of the coordinate system for the surgical instrument; and
a third correspondence computing means for computationally determining the transformation between the coordinate system for the image and the coordinate system for the surgical instrument on the basis of the outputs of the first and second correspondence computing means.
According to a 19th aspect of the present invention, there is provided a surgical operation navigating system comprising:
a coordinate computing means for computationally determining the coordinates of markers on a first reference frame fitted to a subject of medical treatment in a tomographic image of the subject in terms of a coordinate system uniquely defined for the tomographic image for examination, the reference frame having three or more than three markers detectable at least either in an X-ray image or in an MRI image thereof, the markers being arranged at predetermined positions not connectable by a straight line;
a correspondence computing means for computationally determining the transformation between the coordinate system for the tomographic image for examination and a coordinate system defined for the real space containing the markers on the basis of the output of the coordinate computing means and the coordinates of the markers as determined in terms of the coordinate system for the real space; and
a correcting means for correcting the result of the correspondence computing means on the basis of the coordinates of a second reference frame as determined during a surgical operation in terms of the coordinate system for the real space.
According to a 20th aspect of the present invention, there is provided a reference frame comprising:
an anchoring means for rigidly anchoring the reference frame to a subject of medical treatment by utilizing at least three undulated spots on the surface of the body of the subject; and
at least three markers arranged on the frame at positions not connectable by a straight line,
the markers containing a material adapted to make them detectable at least either in an X-ray image or in an MRI image of the frame.
According to a 21st aspect of the present invention, there is provided a surgical operation navigating system using a reference frame adapted to be rigidly anchored to a subject of medical treatment by utilizing at least three undulated spots on the surface of the body of the subject, the system comprising:
an image acquisition means for acquiring images of the subject for medical examination with the reference frame fitted to the subject and carrying at least three markers thereon at the positions not connectable by a straight line, the markers containing a material adapted to make them detectable at least either in an X-ray image or in an MRI image of the frame;
a marker position detecting means for detecting the positions of the markers in terms of the coordinate system for the image for examination;
a marker detecting means for detecting the markers on the frame fitted to the subject in the real space; and
an registering means for registering the coordinates of the image for examination and those of the subject by registering the coordinates of the marker positions as detected by the marker position detecting means and the coordinates of the markers as detected by the marker detecting means.
According to a 22nd aspect of the present invention, there is provided a reference frame comprising:
fitting means for fitting the reference frame with a subject of medical treatment at least three spots along the undulations of the surface thereof; and
markers formed by combining a material easily detectable in an image of a first examining method and a material easily detectable in an image of a second examining method.
According to a 23rd aspect of the present invention, there is provided a calibration apparatus for computing positional/orientational transformation between a patient to be subjected to a surgical operation and a tomographic image of the patient by using the corresponding relationship between the coordinates of first markers on a reference frame fitted to the patient in the image and the coordinates of the reference frame in the real space, the apparatus comprising:
a coordinate detecting means for fitting (second) markers other than the reference frame to the patient and determining the coordinates of the markers on the image by using the coordinates of the markers in the real space and the corresponding relationship; and
a registering means for computing positional/orientational transformation between the patient and the image of the patient by using the coordinates of the markers determined by the coordinate detecting means.
According to a 24th aspect of the present invention, there is provided an operative calibration apparatus of computing positional/orientational transformation between a patient to be subjected to a surgical operation and a tomographic image of the patient, the apparatus comprising:
a reference frame to be fitted to the patient, the reference frame being adapted to be removably placed on the patient and provided thereon with a plurality of first markers;
a first detecting means for taking a tomographic image of the patient carrying the reference frame thereon and determining the coordinates of the markers appearing in the image of the patient in terms of a coordinate system defined for the image;
a second detecting means for fitting a plurality of second markers to the patient carrying the reference frame and determining the coordinates of the first markers and those of the second markers in terms of a coordinate system defined for the real space;
a relationship computing means for computing the positional/orientational transformation between the coordinate system defined for the real space and the coordinate system defined for the image on the basis of the coordinates of the first markers in the coordinate system defined for the real space determined by the first detecting means and those of the first markers in the coordinate system defined for the image;
a coordinate computing means for determining the coordinates of the second markers in the coordinate system defined for the image by using the coordinates of the second markers in the coordinate system defined for the real space determined by the second detecting means and the positional/orientational transformation determined by the relationship computing means; and
a registering means for computing positional/orientational transformation between the patient and the image of the patient by using the coordinates of the second markers determined by the coordinate computing means.
According to a 25th aspect of the present invention, there is provided a calibration apparatus of calibrating the position/orientation of a patient to be subjected to a surgical operation and a tomographic image of the subject by using a reference frame securely fitted to the subject, the apparatus comprising:
markers not found on the reference frame and adapted to be fitted to the patient;
a position defining means for defining the positions of the markers in a coordinate system for the image for examination as defined for the image for examination by using the reference frame; and
a registering section for registering the coordinates of the coordinate system for the image for examination and the coordinate system for the real space by detecting the positions of the markers in the coordinate system for the real space as defined for the real space containing the patient.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.